Unit 2 SCS #13-21 (pg. 181)

13. a. 6 moles
      b. 5 moles
      c. 5 moles

14. a. 2 moles
      b. 621 grams
      c. 28 grams
      d. 415 grams

15. The actual mass is 66.6666666% but since the numbers continue forever, you would round it up to 67%. 

16. a. 87%
      b. 53%
      c. 40%

17. a. 68%
      b. 10%
      c. 6.8%
      d. 







18. a. Reusing is when something is used more than once. Recycling is when you convert an object into a new object.
      b. Reusing: water bottles, paper
          Recycling: cans, glass, plastic

19. a. water, air, soil
      b. minerals, fossil fuels

20. a. reusing
      b. recycling
      c. reusing

21. The glass of from a lightbulb cannot be reused but newspaper can be reused and recycled. The life of a lightbulb is much shorter than newspaper since it can't be reused, but it can be recycled.